I greatly enjoyed your game overall, however level 15 and 20 of insane both were interesting yet leave a bit to be desired.
For example, in both levels the "easy" way to beat them was just to buy the best healing and hp item available at that time and stick that in every slot, rather then an actual skill based attempt to change strategy. While refreshingly different, it wasn't actually challenging in that regard. Otherwise the rest of the game was fantastic and I enjoyed it greatly although balance is a bit of a concern.
For the others my strategy for all levels except 15,20 insane was to max 5 bullets, max lucky strike, max RoF, then fill remaining slots with damage boosters. I never used any consumables, and I stick to stat boosting bots more then actual damage dealing bots although for a short time, the collision bots do more damage then you on normal mode.
Here's a trick for double progress. Hold down ctrl to see both white circles and then move them so that they are side to side. Then hold down shift as well to move the white circles up together so that they are both on the top half. Then every click you make will result in two clicks instead of one for double progress. You can release shift after you have moved the two up to the top, you just need to continue holding CTRL.
The excalibur makes things a little too easy. I could sit in the lower right wrecking tanks all day. Since the only ones who could shoot backwards were emp shots, I had nothing to fear.
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